Cancer of the thyroid, goitrogenesis and thyroid function in syrian (golden) hamsters

Abstract

Goitrogenesis and an increased frequency of cancer of the thyroid was induced by an iodine-deficient rice diet or propylthiouracil. Goitrogenesis but not the occurrence of cancer of the thyroid was inhibited by supplementation of the rice diet with potassium iodide. Female hamsters were much more susceptible to goitrogenesis but not to cancer of the thyroid. Measures of thyroid function gave similar results in both sexes. Hamsters on the rice diet had normal serum PBI levels, markedly enhanced thyroidal affinity for 131I and subnormal or non-detectable levels of serum inorganic-iodide (I). Animals given propylthiouracil had subnormal levels of PBI, inconsistently subnormal thyroidal affinity for 131I and normal serum I. Serum calcium levels were subnormal in hamsters fed rice for 9 months or longer. The TSH-dependent characteristics of thyroid tissue appear necessary for thyroid cancerogenesis but the relationship between marked hyperplasia, due to chronically high TSH levels, and the frequency of cancer of the thyroid is obscure for several reasons.